U.S. Pat. No. 6,776,235 “Hydraulic fracturing method”, filed by Schlumberger on Jul. 23, 2002, discloses a method and means for optimizing fracture conductivity. The well productivity is increased by sequential injection into the wellbore of alternate stages of fracturing fluids having a contrast in their ability to transport proppants to fracture, or having a contrast in the amount of transported proppants, to improve proppant placement. The propped fractures obtained following this process have a pattern characterized by a series of proppant clusters spread along the fracture. In other words, solid particles clusters form “islands” that keep the fracture open along its length and provide a lot of channels for the formation fluids to circulate.
U.S. Pat. No. 7,281,581 “Methods of hydraulic fracturing and fractures propping in subterranean formations”, filed by Halliburton on Dec. 1, 2004, discloses methods of heterogeneous proppant placement, which comprise forming a plurality of proppant aggregates, each proppant aggregate comprising a binding fluid and a filler, and introducing a plurality of proppant aggregates into at least one fracture.
U.S. Pat. No. 7,044,220 “Compositions and methods to improve proppant pack permeability and fracture conductivity in a subterranean well”, filed by Halliburton on Jul. 27, 2003, discloses a hydraulic fracturing treatment with a proppant composition, comprising proppant filler solid particles and material capable of undergoing an irreversible degradation downhole; introducing the proppant composition to the fracture; and allowing the proppant composition to form a proppant matrix having voids in the fracture.
Patent application US 2008/0135242 “Heterogeneous proppant placement in a fracture with removable channelant filler”, filed by Schlumberger on Dec. 8, 2006, (U.S. Pat. No. 7,581,590 (B2), U.S. Pat. No. 8,066,068 (B2)) discloses a method comprising injection, through a wellbore into fracture, of fracturing fluid comprising proppant and channel-forming filler, called a channelant, heterogeneous placement of proppant in the fracture in a plurality of proppant clusters or islands, spaced apart by the channelant, and removal of channelant filler to form open channels around the propping pillars for fluid flow from the formation through the fracture toward the wellbore.
Patent application US 2008/0128131 “Methods for enhancing fracture conductivity in subterranean formations”, filed by Halliburton on Dec. 5, 2006, (U.S. Pat. No. 8,082,994 (B2)), discloses injection of a displacement fluid into a propped fracture in a subterranean formation and formation of at least one channel in the propped fracture.
Patent application WO 2007/086771 “Methods for hydraulic fracturing of subterranean formation”, filed by Schlumberger on Dec. 5, 2006, (U.S. Pat. No. 8,061,424 (B2)), discloses economically effective methods for hydraulic fracturing of a subterranean formation that ensures improvement of hydraulic fracture conductivity because of forming strong proppant clusters uniformly placed in the fracture throughout its length. One of these methods comprises: a first step that involves injection into a wellbore of fracturing fluid containing thickeners to create a fracture in the formation; and a second step that involves periodic introduction of proppant into the injected fracturing fluid to supply the proppant into a created fracture, to form proppant clusters within the fracture to prevent fracture closure and channels for formation fluids to circulate between the clusters. Wherein the second step or its sub-steps involve additional introduction of either a reinforcing or consolidation material or both, thus increasing the strength of proppant clusters formed in the fracturing fluid.
The solutions known in the prior art are focused on the possibility for proppant (proppant) heterogeneous pack formation, while the increase of well lifetime due to lower impact of fracturing fluid on the fracture walls and proppant clusters (islands) is neglected.
Accordingly, in the prior art there is a gap in the creation of a mechanism of well lifetime increase by reducing the fluid impact on fracture walls and proppant clusters.